Microelectromechanical systems (MEMS) include micro mechanical elements, actuators, and electronics. Micromechanical elements may be created using deposition, etching, and or other micromachining processes that etch away parts of substrates and/or deposited material layers or that add layers to form electrical and electromechanical devices. One type of MEMS device is called an interferometric modulator. As used herein, the term interferometric modulator or interferometric light modulator refers to a device that selectively absorbs and/or reflects light using the principles of optical interference. In certain embodiments, an interferometric modulator may comprise a pair of conductive plates, one or both of which may be transparent and/or reflective in whole or part and capable of relative motion upon application of an appropriate electrical signal. In a particular embodiment, one plate may comprise a stationary layer deposited on a substrate and the other plate may comprise a metallic membrane separated from the stationary layer by an air gap. As described herein in more detail, the position of one plate in relation to another can change the optical interference of light incident on the interferometric modulator. Such devices have a wide range of applications, and it would be beneficial in the art to utilize and/or modify the characteristics of these types of devices so that their features can be exploited in improving existing products and creating new products that have not yet been developed. One area where constant improvement is needed is the light guides which are utilized in the flat panel displays.
Current light technologies for reflective flat panel displays are relatively expensive and difficult to fabricate. In a conventional approach, a light guide consists of two pieces of glass fastened together with a sealing agent, such as a bead of epoxy between the two pieces of glass. In the conventional approach, a piece of plastic is fabricated which has a “stairstep” pattern on it. A light guide is attached to the edge of this discrete piece of plastic, and the light is bounced through the plastic. At certain points where the light hits the stairstep structure the light will bounce down into the display.
The “stairstep” features on such a piece of glass require a manufacturing process which is very difficult to utilize using low cost molding methods. What is generally required is to make an expensive molding tool, which can then only be used for fabricating a limited number of parts. The light is very sensitive to the level of defects which may result from the “stairstep” feature. If defects such as a particle in the mold, or a burr in the mold occur, such defects will appear as optical defects to the viewer. Ghosting effects may also result, or double images, as a result of this conventional manufacturing process.
Accordingly, what is needed is a system and method for overcoming the above-mentioned problems. The present invention addresses such a need.